Apparatus for controlling hybrid automatic repeat request (HARQ) in a mobile communication system

ABSTRACT

An apparatus for controlling a Hybrid Automatic Repeat Request (HARQ) is provided. In the apparatus, a physical layer includes a decoder for decoding a control message received over the packet data control channel, a demodulator for demodulating packet data received over the packet data channel, and a turbo decoder for decoding the demodulated packet data. A physical layer&#39;s HARQ controller determines whether to demodulate and decode the received packet data depending on a decoding result of the control message, outputs the decoded control message to the demodulator and the turbo decoder for demodulation and decoding of the received packet data, controls output of a response signal according to decoding result of the packet data, and delivers the turbo-decoded packet data to an upper layer.

PRIORITY

[0001] This application claims priority under 35 U.S.C. § 119 to anapplication entitled “Apparatus and Method for Controlling HARQ in aMobile Communication System” filed in the Korean Intellectual PropertyOffice on Oct. 24, 2002 and assigned Serial No. 2002-65355, the contentsof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to an apparatus andmethod for controlling Automatic Repeat reQuest (ARQ) in a high-speeddata transmission system, and in particular, to an apparatus and methodfor controlling hybrid automatic repeat request(HARQ) in a high-speeddata transmission system.

[0004] 2. Description of the Related Art

[0005] Mobile communication systems have been developed to provide ahigh-quality call service to moving users. With the development ofmobile communication systems, research is being conducted on a methodfor transmitting increasing amounts of data to users. In addition,mobile communication systems have already been switched from an analogsystem to a digital system. Using the digital system, the mobilecommunication systems can now transmit increased amounts of data tousers at higher speeds.

[0006] Generally, in digital mobile communication systems where avariation in channel condition is significant and different types ofservice traffic channels coexist with each other, a hybrid automaticrepeat request (hereinafter referred to as “HARQ”) scheme is used tomeet a demand for high-speed data transmission, i.e., to increasetransmission throughput. Particularly, as commercialization of ahigh-speed data transmission service is realized, analyze and researchare actively performed on technology for efficiently applying a HARQscheme using error correction codes with a variable code rate, ratherthan a HARQ scheme using existing error correction codes with a fixedcode rate. For a channel structure for high-speed transmission, a methodof using high-level modulation such as 8-ary phase shift keying (8-PSK)and 16-ary quadrature amplitude modulation (16-QAM) beside the generalbinary phase shift keying (BPSK) or quadrature phase shift keying(QPSK), as a modulation scheme, is also taken into consideration.

[0007] Currently, a Code Division Multiple Access 2000 for SpreadingRate 1 (CDMA2000 1×) Evolution Data and Voice (EV-DV) system, which is anew transmission standard of a synchronous Third Generation PartnershipProject (3GPP2) CDMA system, has adopted a coding scheme usingquasi-complementary turbo codes (QCTC) as its standard. Thequasi-complementary turbo codes provide a variable code rate to a codingscheme for an HARQ scheme over high-speed data and provide improvementin soft combining performance using HARQ. In the EV-DV system, packetdata transmission/reception is performed by an HARQ or fast HARQoperation of a physical layer. This will be described in detail withreference to FIGS. 1 and 2.

[0008]FIG. 1 is a block diagram illustrating a relationship between anupper layer and a physical layer for ARQ processing commercially.Referring to FIG. 1, a physical layer 110 decodes data received over aradio channel and makes decoded frame data. The physical layer 110delivers the decoded frame data to a MAC layer 120 as called an upperlayer. The MAC layer 120 determines whether the decoded frame datareceived from the physical layer 110 has a Protocol Data Unit (MuxPDU)error. When an error occurs, the MAC layer 120 retransmits the defectivedata. However, when no error occurs, the MAC layer 120 transmits a newframe. When processing is performed in the MAC layer 120, since datadecoded in the physical layer must be delivered to the upper layer to beprocessed, ARQ processing speed is decreased undesirably. In addition,since high-speed data process must be performed, a load on the MAC layer120 is increased. Hence, there have been proposed methods in which anoperation performed in the upper layer is performed in the physicallayer. Such methods provide a structure in which an operation in thephysical layer, i.e., hardware, is performed in the same way as anoperation in software. In this context, if part of the operation of FIG.1 is applied to the physical layer, a structure for processing part ofan ARQ operation in the physical layer is provided as illustrated inFIG. 2.

[0009]FIG. 2 is a block diagram illustrating a relation between an upperlayer and a physical layer for improved fast (physical) HARQ processing.With reference to FIG. 2, a description will now be made of arelationship between an upper layer and a physical layer for improvedfast HARQ processing. A structure of FIG. 2 is realized when thestructure of FIG. 1 is performed in the physical layer. It should benoted that such a structure has never been proposed up to now. In otherwords, it should be noted that the concept of FIG. 2 is expected byapplying currently proposed methods, this has never been actuallyimplemented, and no discussion has been made on the operations that willbe described in the detailed description section below.

[0010] In FIG. 2, part of an ARQ operation that has been performed in aMAC layer 230 is performed in a physical layer or its intermediatelayer, for fast ARQ response and processing. That is, in this scheme, aphysical layer 200 has a basic physical layer 210 performing the sameoperation as that of FIG. 1, and an HARQ controller 220. The HARQcontroller 220 performs part of the operation that was performed in theconventional MAC layer. Therefore, the HARQ controller 220 is includedin the physical layer in structure, but performs part of an operation ofthe MAC layer 230 since the physical layer determines dataretransmission, a processing time for the same data is shortened.

[0011] In addition, NAK transmission in the upper layer cannot performsoft combining for the same data, because the physical layer canmaintain a soft combined value for each symbol. However, since datasymbols delivered from the physical layer to the MAC layer are allexpressed with a binary value (0 or 1), although a symbol is repeated byretransmission, there is no way to soft combine the repeated symbol. Theonly method is a majority voting method for calculating the number of 0sand 1s for symbols having a binary value, and comparing the number of 0swith the number of 1s thus to decide a majority symbol. However, thismethod also cannot be used in the upper layer because of its plentycalculations. On the contrary, NAK transmission in the physical layerenables soft combining of code symbols for the same encoder packet,contributing to efficient utilization of channel resources. Therefore,it is preferable to dispose the HARQ controller 220 under a multiplexingsublayer 230 of the MAC layer. That is, it is preferable for the MAClayer to perform an operation of the physical layer.

[0012] This structure has a fast processing time compared with aconventional ARQ control method operating based on a Radio Link Protocol(RLP). This will now be compared with the existing method. In theconventional method of FIG. 1, a NAK signal is received from one packettransmission, and a round trip delay of a minimum of about 200 msecoccurs up to a time when a retransmission packet is transmitted due tothe NAK signal. On the contrary, in the method of FIG. 2, HARQ generatesa very short round trip delay of a minimum of about severalmilliseconds. Therefore, it has a very good structure for implementingadaptive modulation and coding (AMC).

[0013] In order to actually operate HARQ with the structure of the upperlayer and the physical layer of FIGS. 1 and 2, a retransmission protocolof a transmitter for a retransmission request (i.e., NAK transmittedfrom a receiver) is required. For this, the 3GPP2 CDMA2000 1×EV-DVsystem uses Asynchronous and Adaptive Increment Redundancy (AAIR), andthis will be described below.

[0014] A base station asynchronously performs packet transmission to acorresponding mobile station according to the quality of a forwardchannel. At this point, a modulation scheme and a code rate of thetransmission packet are adaptively applied according to a channelcondition. In addition, a packet transmission failure during initialtransmission is retransmitted, and during retransmission, a code symbolpattern that is different from that at the initial transmission can betransmitted. Such an AAIR retransmission scheme increases asignal-to-noise ratio (SNR) of packet data due to an increase in thenumber of retransmissions, and increases a coding gain due to a decreasein a code rate, thereby improving transmission/reception performance ofpacket data.

[0015] A channel used for transmission of forward packet data in the1×EV-DV system includes a forward packet data channel (F-PDCH) forpayload traffic and a forward packet data control channel (F-PDCCH) forcontrolling the F-PDCH. F-PDCH is a channel for transmitting an encoderpacket (EP) which is a transmission data block, and a maximum of up to 2channels are used to simultaneously transmit their encoder packets to 2mobile stations by time division multiplexing (TDM)/code divisionmuitiplexing (CDM). An encoder packet is encoded by a turbo encoder, andthen some of the encoded symbols are selected as a subpacket havingspecific Increment Redundancy (IR) pattern by OCTC symbol selection. Thesubpacket is a transmission unit for initial transmission andretransmission, and at each transmission, an IR pattern of a subpacketis identified by a subpacket identifier (SPID). A modulation scheme(QPSK, 8PSK or 16QAM) and a transmission slot length (1, 2 or 4 slots)of the subpacket are determined according to forward channel qualityinformation transmitted from a mobile station and resources (the numberof Walsh codes and power assignable to F-PDCH) of a base station.

[0016] Information related to demodulation and decoding of F-PDCH ismultiplexed with F-PDCH through other orthogonal channels for the sameslot period, and then transmitted over the F-PDCCH which is a controlchannel. Information included in the F-PDCCH is very important forperforming a physical layer's HARQ operation by a mobile station, andrequires the following:

[0017] 1) fragmented Walsh code information available for F-PDCH everyseveral tens to several hundreds milliseconds;

[0018] 2) MAC_ID: MAC_ID of a mobile station (MS) to which F-PDCH isassigned;

[0019] 3) ACID: ID for identifying 4 ARQ channels (ARQ channel ID);

[0020] 4) SPID: ID for identifying an IR pattern of a subpacket;

[0021] 5) EP_NEW: information for distinguishing two consecutive encoderpackets in the same ARQ channel;

[0022] 6) EP_SIZE: a bit size of an encoder packet; and

[0023] 7) LWCI (Last Walsh Code Index): information on a Walsh code usedfor F-PDCH.

[0024] Meanwhile, packet data reception in a mobile station is performedfrom decoding of F-PDCCH. A mobile station first decodes F-PDCCH todetermine whether its own packet is being transmitted, and if it isdetermined that the transmitted packet is its own packet, the mobilestation performs demodulation and decoding on F-PDCH. If a currentlyreceived subpacket is a subpacket that was retransmitted for apreviously received encoder packet, the mobile station performs decodingafter code-combining the currently received subpacket with code symbolsof an encoder packet that was previously received and stored therein. Ifthe decoding is successful, the mobile station transmits an ACK signalover a reverse ACK/NAK transmission channel (R-ACKCH), allowing the basestation to transmit a subpacket for the next encoder packet. If thedecoding is not successful, the mobile station transmits a NAK signal,requesting the base station to transmit a subpacket for the same encoderpacket.

[0025] A unit for which a physical layer's HARQ operation is performedon one encoder packet is called an “ARQ channel.” In the CDMA20001×EV-DV system, a maximum of 4 ARQ channels can simultaneously operate,and these are called “N=4 fast HARQ channels.”

[0026] In the 1×EV-DV standard, it is provided that ACK/NAK Delaynecessary for performing by a mobile station a packet receptionoperation and transmitting ACK/NAK and the number of simultaneouslyavailable ARQ channels should be provided to a base station by themobile station, and this becomes an implementation issue for a mobilestation. Therefore, a possible ACK/NAK Delay supported by the mobilestation is 1 slot (=1.25 msec) or 2 slots (2.5 msec), and the possiblenumber of ARQ channels is 2, 3 or 4. With reference to FIGS. 3 and 4, adescription will now be made of an operation depending on ACK/NAK Delayand the number of ARQ channels.

[0027]FIG. 3 is a timing diagram between a base station and a mobilestation for ACK/NAK Delay=1 slot in HARQ in a mobile communicationsystem, and FIG. 4 is a timing diagram between a base station and amobile station for ACK/NAK Delay=2 slots in HARQ in a mobilecommunication system.

[0028] It will be assumed in FIGS. 3 and 4 that a forward packet datachannel (F-PDCH) is assigned to a mobile station A. In addition, for theconvenience of explanation, indexes are sequentially assigned to timeslots of both a base station (BS) and a mobile station (MS) from 0^(th)time slot beginning at a particular time. Further, in FIGS. 3 and 4,A(x,y) has the following meaning. Hatched parts refers to data to betransmitted to the mobile station A. In addition, ‘x’ refers to an ARQchannel, and ‘y’ refers to an index for distinguishing an IR pattern forthe same encoder packet. Based on this, a description will now be madeof FIG. 3 in which ACK/NAK Delay is 1 slot.

[0029] Referring to FIG. 3, data from a base station is transmitted to amobile station A at a 0^(th) slot. Then, the mobile station A receivesthe packet data at the same slot. In FIGS. 3 and 4, the base station andthe mobile station have different slot start points due to transmissiondelay occurring between the mobile station and the base station on thebasis of an absolute time. At this point, the base station transmitspacket data and a packet data control signal over a forward packet datachannel (F-PDCH) and a forward packet data control channel (F-PDCCH),respectively. Then, the mobile station A determines whether the data hasan error, for a one-slot processing time, and thereafter, transmits ACKor NAK to the base station. The “processing time” refers to a timerequired for performing demodulation and decoding on received packetdata for one slot, and transmitting the result at the next slot over areverse channel (R-ACKCH). For example, in FIG. 3, NAK is transmitted.The base station then receives the NAK at a 3^(rd) slot, and schedulesretransmission of the defective data at a 4^(th) slot. Thereafter, thebase station transmits data of a different pattern for the same encoderpacket according to the scheduling result.

[0030] Next, a description will be made of FIG. 4 in which ACK/NAK Delayis 2 slots. It will be assumed in FIG. 4 that an error has occurred in afirst data packet among the data packets transmitted from a base stationto a mobile station A, and the description will be focused on the firstdata packet. Since the delay time is 2 slots, the base stationcontinuously transmits packet data to the mobile station A at a 0^(th)slot, a 1^(st) slot and a 2^(nd) slot. The mobile station then checks anerror of the data transmitted at the 0^(th) slot for a period of the1^(st) to the 2^(nd) slots, checks an error of the data transmitted atthe 1^(st) slot for a period of the 2^(nd) to 3^(rd) slots, and checksan error of the data transmitted at the 2^(nd) slot for a period of the3^(rd) to 4^(th) slots. ACK/NAK for the data received at the 3^(rd)slot, ACK/ NAK for the data received at the 1^(st) slot is transmittedat the 4^(th) slot, and ACK/NAK for the data received at the 2^(nd) slotis transmitted at a 5^(th) slot. If the base station receives, at the4^(th) slot, NAK for the packet data transmitted at the 0^(th) slot, thebase station performs, at the next slot, retransmission on an encoderpacket transmitted at the 0^(th) slot. The retransmitted packet data isthe same packet as the previously transmitted packet but has a differentIR pattern.

[0031] As can be understood from FIGS. 3 and 4, the mobile stationperforms synchronous ACK/NAK transmission in which the mobile stationmust transmit ACK or NAK for a received packet after a lapse of 1 slotor 2 slots. The base station performs asynchronous ACK/NAK transmissionin which the base station can transmit a packet at any slot afterreceiving ACK/NAK for a packet previously transmitted by the mobilestation for the same ARQ channel.

[0032] In addition, FIGS. 3 and 4 illustrate a 1-channel ARQ operationand a 4-channel ARQ operation, respectively. In the 1-channel ARQoperation of FIG. 3, data transmission to one mobile station uses only apart of base station resources, decreasing a packet data rate of acorresponding mobile station. In contrast, in the 4-channel ARQoperation of FIG. 4, one mobile station can use the entire resources ofthe base station, so a corresponding mobile station can obtain a maximumpacket data rate.

[0033] As described above, it is possible to enable fast ARQ responseand processing by moving ARQ control that was achieved in theconventional upper layer, under a multiplexing layer. However, this is amere logical resolution in the standard, and the following problemsarise in its actual implementation.

[0034] First, currently, most systems implement an upper layer includinga multiplexing layer by software loaded in a central processing unit(CPU). However, in the case of a mobile station, its CPU does not havehigh processing speed and capability. Therefore, in implementing an HARQprotocol requiring a fast response in the CPU, overload may occur in aclock of the CPU. As a result, the mobile station may fail to performits normal operation. Particularly, such a problem serves as a bighindrance to implementation, when power consumption of the mobilestation is an implementation limitation factor of the system.

[0035] Second, transmission interrupt of coded data and a processingdelay due to the interrupt, which impose an overload to the CPU, must bereduced to process high-speed transmission data. Therefore,consideration should be taken for a method for reducing data processinginterrupts which may occur every 1.25 msec.

[0036] Third, in order to support N-channel HARQ, N independent HARQcontrollers are required. Therefore, if N is increased, the number ofHARQ controllers is also increased, causing an increase in powerconsumption and complexity. Thus, in implementation, the number of HARQcontrollers must be minimized.

[0037] Fourth, in order to support N-channel HARQ, N independent turbodecoders are required. Therefore, if N is increased, the number of turbodecoders is also increased, causing an increase in power consumption andcomplexity. Thus, in implementation, the number of turbo decoders mustbe minimized.

[0038] Fifth, in the standard, ACK_DELAY=1 slot and ACK_DELAY=2 slotsdescribed in conjunction with FIGS. 3 and 4 are exclusive options.However, in implementing a mobile station, a structure for varying anoperating clock of the mobile station by selectivelydemultiplying/multiplying the operating clock for low power consumptionis considered, so a mobile station's structure capable of applying allACK_DELAYs in one mobile station must be designed.

[0039] Sixth, unlike the conventional data traffic, an encoder packetwhich is a data block transmitted over a forward packet data channel(F-PDCH) can change its transmission scheme every 1.25 msec. Therefore,a new structure for transmitting, every 1.25 msec, channel structureinformation that is transmitted once during setup of a data channel isrequired.

[0040] Finally, the other control information necessary for applicationof a mobile station is transmitted by a base station over a forwardpacket data control channel (F-PDCCH) which is a traffic controlchannel. Therefore, the mobile station must efficiently perform anoperation of detecting the control information and delivering thedetected control information to the upper layer within a short time.

SUMMARY OF THE INVENTION

[0041] It is, therefore, an object of the present invention to providean apparatus and method for resolving the problems of the conventionaltechnology.

[0042] It is another object of the present invention to provide anapparatus and method for reducing a load of a CPU.

[0043] It is further another object of the present invention to providean apparatus and method for reducing power consumption of a mobilestation in an HARQ control apparatus.

[0044] It is yet another object of the present invention to provide anapparatus and method for reducing a load of a CPU caused by a maximumdriving clock in an HARQ control apparatus.

[0045] It is still another object of the present invention to provide anapparatus and method for reducing a data processing time in an HARQcontrol apparatus.

[0046] It is still another object of the present invention to provide asimple control apparatus and method which is not dependent on the numberof channels when N-channel HARQ is supported in an HARQ controlapparatus.

[0047] It is still another object of the present invention to provide acontrol apparatus and method for preventing complexity from beingincreased according to the number of channels in an HARQ controlapparatus.

[0048] It is still another object of the present invention to provide anapparatus and method for processing all received packets regardless ofthe number of channels, using a small number of turbo decoders.

[0049] It is still another object of the present invention to provide anapparatus and method capable of supporting both ACK_DELAY=1 slot andACK_DELAY=2 slots.

[0050] It is still another object of the present invention to provide anapparatus and method for controlling calculation and setting of controlchannel parameters generated every slot after initial setup of a packetdata channel (PDCH).

[0051] It is still another object of the present invention to provide anapparatus and method for calculating and modifying parameters fordemodulation and decoding of a traffic channel in a mobile communicationsystem.

[0052] It is still another object of the present invention to provide anapparatus and method for rapidly delivering control information of atraffic control channel to an upper layer.

[0053] To substantially achieve the above and other objects, there isprovided an apparatus for decoding a control message received over apacket data control channel, demodulating and decoding packet dataaccording to a decoding result of the packet data control channel,generating a decoding result as a response signal, and transmitting theresponse signal, in a mobile communication system that simultaneouslytransmits a control message over the packet data control channel andpacket data over a packet data channel and supports hybrid automaticrepeat request (HARQ). The apparatus comprises a physical layerincluding a decoder for decoding a control message received over thepacket data control channel, a demodulator for demodulating packet datareceived over the packet data channel, and a turbo decoder for decodingthe demodulated packet data; and a physical layer's HARQ controller fordetermining whether to demodulate and decode the received packet datadepending on a decoding result of the control message, outputting thedecoded control message to the demodulator and the turbo decoder duringdemodulation and decoding of the received packet data, controllingoutput of a response signal according to a decoding result of the packetdata, and delivering the turbo-decoded packet data to an upper layer.

[0054] The physical layer's HARQ controller comprises an HARQ statemachine for controlling state transition of an initial state forinitializing parameters while waiting for a control message to bereceived over the packet data control channel received from the physicallayer, a decoding state for decoding the control message, a controlstate for calculating the decoding result, a demodulation state fordemodulating packet data on the packet data channel, a decoding statefor turbo decoding the demodulated packet data, and a response state fortransmitting the turbo-decoding result; and a state function section forcontrolling state transition of the HARQ state machine depending on aprocessing result of the physical layer.

[0055] Further, the apparatus comprises a data path processor forcontrolling a processing path of data received over the packet datachannel.

[0056] Further, the apparatus comprises an output buffer controller forcontrolling an output buffer of the physical layer, which stores dataobtained by demodulating and decoding data received over the packet datachannel.

[0057] Preferably, the HARQ state machine is dualized.

[0058] If a response delay time comprises 2 slots, each of the dualizedHARQ state machines alternately controls the state transition for 2slots for the data received over the packet data channel.

[0059] If a response delay time comprises 2 slots, the HARQ statemachine controls transition to a waiting state for waiting for turbodecoding by a turbo decoder of the physical layer to be done when theturbo decoder is in operation.

[0060] The state function section comprises first state processors forperforming control operations of the associated dualized HARQ statemachines in the initial state; a second state processor for performingcontrol operations of the HARQ state machines in the control state; athird state processor for performing control operations of the HARQstate machines in the demodulation state; a fourth state processor forperforming control operations of the HARQ state machines in the waitingstate; a fifth state processor for performing control operations of theHARQ state machines in the decoding state; and sixths state processorsfor performing control operations of the associated HARQ state machinesin the response state.

[0061] The physical layer comprises one data channel turbo decoder.

[0062] To substantially achieve the above and other objects, there isprovided a method for controlling an operation of receiving packet dataand a control message in a physical layer for decoding a control messagereceived over a packet data control channel, demodulating and decodingpacket data according to a decoding result of the packet data controlchannel, generating a decoding result as a response signal andtransmitting the response signal, and a hybrid automatic repeat request(HARQ) controller included in the physical layer, in a mobilecommunication system that simultaneously transmits a control messageover the packet data control channel and packet data over a packet datachannel and supports hybrid automatic repeat request. The methodcomprises the steps of: (a) initializing parameters of the HARQcontroller in the physical layer during initial drive, and uponreceiving the control message, controlling decoding of the receivedcontrol message; (b) calculating a parameter of the control messageaccording to a decoding result of the packet data control channel, andperforming a fast HARQ protocol; (c) controlling demodulation of packetdata received over the packet data channel according to the calculatedparameter; (d) controlling turbo decoding of the demodulated dataaccording to the calculated parameter; and (e) transmitting an errorcheck result of the turbo decoded data.

[0063] Further, the method comprises the step of avoiding performingsucceeding states and returning to the step (a), if the calculatedparameter comprises a non-creatable parameter.

[0064] Further, the method comprises the steps of determining whetherthe parameter is a message for control hold mode/cell switching, if thecalculated parameter is a non-creatable parameter; and delivering themessage to the upper layer, if the parameter is a message for controlhold mode/cell switching.

[0065] Further, the method comprises the step of transitioning to aninitial state if the parameter is not a message for control holdmode/cell switching.

[0066] Further, the method comprises the step of waiting until use of adata channel turbo decoder is ended and then proceeding to the step (d),if the data channel turbo decoder of the physical layer is in use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The above and other objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

[0068]FIG. 1 is a block diagram illustrating a relation between an upperlayer and a physical layer for Automatic Repeat Request (ARQ) processingaccording to the prior art;

[0069]FIG. 2 is a block diagram illustrating a relationship between anupper layer and a physical layer for improved fast (physical) HybridAutomatic Repeat Request (HARQ) processing;

[0070]FIG. 3 is a timing diagram illustrating a relationship between abase station and a mobile station for ACK/NAK Delay=1 slot in HARQ in amobile communication system;

[0071]FIG. 4 is a timing diagram illustrating a relationship between abase station and a mobile station for ACK/NAK Delay=2 slots in HARQ in amobile communication system;

[0072]FIG. 5 is a block diagram illustrating an interface betweenperipheral blocks centering on an HARQ controller according to anembodiment of the present invention;

[0073]FIG. 6 is a block diagram illustrating the connection between anHARQ state machine and a state function section in an HARQ controlleraccording to an embodiment of the present invention;

[0074]FIG. 7 is a state transition diagram illustrating an HARQcontroller according to an embodiment of the present invention;

[0075]FIG. 8 is an operational timing diagram illustrating first orsecond HARQ state machines for ACK/NAK Delay=1 slot;

[0076]FIG. 9 is an operational timing diagram illustrating first andsecond HARQ state machines for ACK/NAK Delay=2 slots;

[0077]FIG. 10 is an activation control timing diagram illustrating firstand second HARQ state machines for ACK/NAK Delay=1 slot according to anembodiment of the present invention;

[0078]FIG. 11 is an activation control timing diagram illustrating firstand second HARQ state machines for ACK/NAK Delay=2 slots according to anembodiment of the present invention;

[0079]FIG. 12 is a state transition timing diagram illustrating a firstHARQ state machine for ACK/NAK Delay=1 slot according to an embodimentof the present invention;

[0080]FIG. 13 is a state transition timing diagram illustrating a firstHARQ state machine and a second HARQ state machine for ACK/NAK Delay=2slots according to an embodiment of the present invention;

[0081]FIG. 14 is a diagram illustrating a control flow between an HARQcontroller and its peripheral devices according to an embodiment of thepresent invention; and

[0082]FIG. 15 is a flowchart illustrating a procedure for controllingrespective states by an HARQ controller during data reception accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0083] An embodiment of the present invention will now be described indetail with reference to the accompanying drawings. In the drawings, thesame or similar elements are denoted by the same reference numerals eventhough they are depicted in different drawings. In the followingdescription, a detailed description of known functions andconfigurations incorporated herein has been omitted for conciseness.

[0084] An apparatus and method of the present invention for resolvingthe foregoing problems will now be described.

[0085] First, most systems implement an upper layer including amultiplexing layer by software loaded in a central processing unit(CPU). Therefore, the present invention proposes a method forimplementing an Hybrid Automatic Repeat Request (HARQ) controller of aphysical layer by hardware in order to resolve a power consumptionproblem and a maximum driving clock problem of a mobile station and toreduce overload of the CPU. If it can be implemented by software withoutaffecting its performance because of excellent performance of the CPU orDigital Signal Processor (DSP), a basic structure of the HARQ controllerproposed in the embodiment of the invention can be implemented bysoftware. Herein, the present invention will be described under theassumption that the HARQ controller is implemented by hardware.

[0086] Second, the present invention enables high-speed data processingby reducing transmission interrupt of coded data and a processing delaydue to the interrupt, which impose an overload on the CPU. To this end,an output buffer controller (OBUFC) is separately installed in an HARQcontroller. The output buffer controller takes full charge of anoperation of transmitting data from a channel decoder to a CPU (orhost). Particularly, the output buffer controller has a capability ofcontrolling a storing time of decoded data, previously set at therequest of the CPU, and adjusts a transmission time of transmission dataso as to satisfy a minimum transmission interrupt interval desired bythe CPU.

[0087] Third, in order to support N-channel HARQ, N independent fastHARQ controllers are required. However, the embodiment of the presentinvention proposes a structure capable of always processing all receivedpackets regardless of the number of channels by using 2 HARQcontrollers. Therefore, it is possible to prevent an increase in powerconsumption and complexity irrespective of an increase in number of thechannels. To this end, the structure includes two state machines: an oddstate machine and an even state machine, and also has a controller forcontrolling the state machines.

[0088] Fourth, in order to support N-channel HARQ, N independent turbodecoders are required. However, the embodiment of the present inventionproposes a structure capable of processing all received packetsregardless of the number of channels by using one turbo decoder.Therefore, it is possible to decrease power consumption and circuitcomplexity irrespective of an increase in the number of channels. Tothis end, the embodiment of the present invention proposes a method inwhich an HARQ controller adaptively determines/controls a start signaland a stop signal for decoding of the one turbo decoder. Further, in thestructure, a “waiting state” is added to each state machine.

[0089] Fifth, the embodiment of the present invention implements an HARQcontroller that supports both ACK_DELAY=1 slot and ACK_DELAY=2 slots.Since in implementing a mobile station, a structure for varying anoperating clock of the mobile station by selectivelydemultiplying/multiplying the operating clock for low power consumptionis considered, so a state machine and a state function of an HARQcontroller are provided to support two modes in which all ACK_DELAYs canbe applied in one mobile station.

[0090] Sixth, unlike the conventional data traffic, an encoder packetwhich is a data block transmitted over a forward packet data channel(F-PDCH) can change its transmission scheme every 1.25 msec. Therefore,as usual, the CPU takes part in only initial setup so as to deliver,every 1.25 msec, channel structure information that is transmitted onceduring setup of a data channel. In addition, calculating and setting ofcontrol channel parameters generated every slot, and calculation andmodification of parameters for demodulation and decoding of a trafficchannel are performed in the HARQ controller.

[0091] Seventh, control information necessary for application of amobile station, transmitted by a base station over a forward packet datacontrol channel (F-PDCCH) which is a traffic control channel, isdetected and then delivered to an upper layer of the CPU within a shorttime. In addition, the message detection result is reflected in thestate machine and a state function according thereto is defined.

[0092] Function of HARQ Controller Upon receiving Evolution Data andVoice (EV-DV) (forward link RC-10) packet data, an HARQ controllercontrols an operation of each block related to the received packet data.Each block related to reception of the packet data operates under thecontrol of the HARQ controller, and after completion of a correspondingoperation, informs the HARQ controller of the completion of thecorresponding operation. The HARQ controller performs the next operationusing the operation completion information from each block. In addition,the HARQ controller stores input information and internal informationfrom each block in its register. By doing so, the HARQ controller canmonitor the progress of an HARQ operation. The control of each block,performed by the HARQ controller, is mainly timing control forperforming an HARQ operation within a given time, and does not includecontrol for a unique operation of each block. In addition, the HARQcontroller determines whether it will perform a normal mode operation oran abnormal mode operation using reception information and internalinformation on a forward packet data control channel (F-PDCCH). The HARQcontroller performs an operation based on the determination result. Theoperation in the abnormal mode is caused by an error in a radio channelstate, and is for improving data reception performance.

[0093] Typical functions of the HARQ controller according to theembodiment of the present invention are as follows:

[0094] (1) The HARQ controller determines whether it will operate in anormal mode operation or an abnormal mode operation according to areception message on F-PDCCH and internal information of the HARQcontroller.

[0095] (2) The HARQ controller controls a demodulation and turbodecoding operation for F-PDCH according to an operation mode.

[0096] (3) The HARQ controller determines information (ACK/NAK orSilence) to be transmitted over an uplink response channel (R-ACKCH).

[0097] (4) The HARQ controller generates an interrupt to an upper layerin order to transfer received data to an output buffer of a turbodecoder.

[0098] (5) The HARQ controller continuously stores and updates relatedinformation every Automatic Repeat Request (ARQ) channel.

[0099] (6) The HARQ controller supports a maximum of 4 ARQ channels.

[0100] (7) The HARQ controller supports all control operations in thecase where ACK/NAK Delay is 1 slot and 2 slots.

[0101]FIG. 5 is a block diagram illustrating an HARQ controller appliedto process an operation of an upper layer by a physical layer and aninterface between peripheral blocks centering on the HARQ controller.With reference to FIG. 5, a description will now be made of respectiveblocks connected to the HARQ controller according to the embodiment ofthe present invention, and an internal structure and operation of theHARQ controller.

[0102] The HARQ controller 300 includes therein 2 HARQ state machines(OHSM/EHSM) 310, an HARQ register (HARQC_REG) 320, a state function anddata path controller 330, and an output buffer controller 340. An HARQoperation is controlled by the HARQ state machines 310 and the statefunction and data path controller 330 among the elements of the HARQcontroller 300. An output buffer connected to a data channel turbodecoder 430 which will be described later, is controlled by the outputbuffer controller 340. Connections of signals input to and output fromthe HARQ controller 300 are schematically illustrated in FIG. 5. Thatis, signals output from a particular internal block are not illustrated.Now, with reference to the accompanying drawings, a description will bemade of respective internal structures and their connections of the HARQcontroller 300 illustrated in FIG. 5.

[0103] The HARQ controller 300 is connected to a processor (CPU or host)400, and can exchange data via a data buss 450 and an address bus 460.Further, the HARQ controller 300 can transmit an interrupt signal to theprocessor 400 via an interrupt line. The HARQ controller 300 isconnected to a control channel decoder (PDCCH_DEC) 410 for decoding datacarried on a packet data control channel, controls an On/Off operationof the control channel decoder 410, and provides a decoding parameterfor the data carried on the packet data control channel. The controlchannel decoder 410 for decoding data on the packet data control channel(PDCCH) decodes data on the packet data control channel based on theparameter received from the HARQ controller 300, and then delivers thedecoded data to the HARQ controller 300 along with a decoding-donesignal.

[0104] The HARQ controller 300 is connected to a data channeldemodulator (PDCH_DEMOD) 420 for demodulating data carried on a packetdata channel, controls an On/Off operation of the data channeldemodulator 420, and provides demodulation parameters and controlsignals to the data channel demodulator 420. The data channeldemodulator 420 then demodulates data carried on the packet datachannel, delivers the demodulated data to the HARQ controller 300, andprovides system time data to the HARQ controller 300.

[0105] The embodiment of the present invention provides a controlleroperating in the EV-DV system. Therefore, data transmitted from theEV-DV system is fundamentally turbo-encoded by a turbo encoder beforebeing transmitted. Therefore, the HARQ controller 300 is connected to adata channel turbo decoder (PDCH_TURBO) 430 for decoding data carried ona packet data channel, and performs an On/Off operation of the datachannel turbo decoder 430. In addition, the HARQ controller 300 providesthe data channel turbo decoder 430 with an intentional stop signal,turbo decoding parameters and control signals, and buffer controlparameters and control signals. The data channel turbo decoder 430 thenturbo-decodes data on a packet data channel based on various parametersand control signals received from the HARQ controller 300, and providesthe HARQ controller 300 with a turbo decoding-done signal, a CRC resultsignal, and a decoding status signal. In addition, the data channelturbo decoder 430 is connected to a data bus and an address bus in orderto store and read data into/from a memory (not shown). The HARQcontroller 300 performs a control operation of delivering data stored ina buffer connected to the turbo decoder 430 to the processor 400.

[0106] The HARQ controller 300 is connected to a response signaltransmitter (RACK_TX) 440, and performs ACK/NAK and Silence control onthe data on a received packet data channel according to its decodingresult. In addition, the response signal transmitter 440 outputstransmission timing information to the HARQ controller 300.

[0107] Operations and states of the HARQ controller 300 will bedescribed with reference to Table 1 below. TABLE 1 ACK_DELAY StateDescription (slot) S1 WAITING_FOR_PDCCH_DEC_DONE 1 & 2 A state where theHARQ controller waits for PDCCH_DEC_DONE to be received from PDCCH_DEC.S2 DEMOD_SIG_GEN 1 & 2 A state where the HARQ controller calculatesparameters for New/Continue Decision of subpacket, Extraction ofSignaling message, and PDCH Demodulation. S3 PDCH_DEMOD 1 & 2 A statewhere the HARQ controller performs PDCH Demodulation. S4WAITING_FOR_TURBO_DE- 2 CODER_TO_USE A state where the HARQ controllerwaits for TURBO decoder to use. S5 TURBO_DECODING 1 & 2 A state wherethe HARQ controller delivers decoding start signal and necessaryparameters to PDCH Turbo decoder and waits for decoding to be done. S6ACK_NAK_TRANSMISSION 1 & 2 A state where the HARQ controller transmitsACK/NAK over Reverse channel after PDCH Turbo decoding is done.

[0108] In Table 1, respective states S1, S2, S3, S4, S5 and S6 representstates defined in order of an operation performed at a particular timein the HARQ controller 300 and a next operation performed thereafter.The respective states S1, S2, S3, S4, S5 and S6 have a mutualrelationship between a previous operation and a next operation. Inaddition, Table 1 illustrates states necessary for when ACK/NAK Delay is1 slot, and states necessary for when ACK/NAK Delay is 2 slots. Forexample, the fourth state S4 represents a state necessary only whenACK/NAK Delay is 2 slots. The respective states of Table 1 will now bedescribed herein below.

[0109] The first state S1 is an ‘initial state’ that is performed when apacket data control channel message being matched to MACID in controldata carried on a packet data control channel (PDCCH) is received or apredetermined control message to be transmitted from a base station to amobile station is received. When the HARQ controller 300 enters thefirst state S1, it waits for decoding of control data carried on apacket data control channel to be completed. That is because the datachannel demodulator 420 can demodulate data on a packet data channelusing control data on a packet data control channel. In addition, theHARQ controller 300 performs a register initialization operation in thefirst state S1, and then transitions to the second state S2 whendecoding of the packet data control channel is completed.

[0110] In the second state S2, the HARQ controller 300 calculatesparameters for demodulation of a packet data channel using variousmessages received as the decoding result of the first state S1. Thesecond state S2 becomes an ‘HARQ control state’. Further, in the secondstate S2, the HARQ controller 300 processes an HARQ protocol in thephysical layer. That is, in the second state S2, the HARQ controller 300calculates a modulation level necessary for demodulation and the numberof Walsh code channels, and delivers the results to the data channeldemodulator 420. In addition, the HARQ controller 300 determines in thesecond state S2 whether a subpacket received in the first state S1 overa packet data channel according to ACID and EP_NEW which are decodingresults of a packet data control channel is new data (initialtransmission data) or retransmitted data. Further, when an upper layercontrol message (or signaling message) is detected according to thedecoding result of the packet data control channel, the HARQ controller300 directly determines ACK/NAK transmission, disregarding anotherprocess. Besides, the HARQ controller 300 performs invalidity test inthe second state S2, and if it is determined that a message that thebase station cannot transmit is received, the HARQ controller 300returns to the first state S1 which is an initial state.

[0111] In the third state S3, the HARQ controller 300 controls the datachannel demodulator 420 to demodulate data carried on a packet datacontrol channel. The third state S3 is a ‘demodulation state’. In thisdemodulation state, a parameter for demodulation of the detection resulton initial transmission data or retransmission data detected in thesecond state S2 is provided to the data channel demodulator 420 todemodulate a subpacket carried on a packet data channel. Therefore, theHARQ controller 300 provides parameters necessary for demodulation tothe data channel demodulator 420, and then waits until demodulation iscompleted. If the demodulation is completed, the HARQ controller 300transitions to the fourth state S4 or the fifth state S5 according tothe number of slots for ACK/NAK Delay.

[0112] In a specific case, the HARQ controller 300 transitions to thefourth state S4. The fourth state S4 is a ‘waiting state’ where the HARQcontroller 300 waits while a subpacket received over a previous packetdata channel is demodulated by an HARQ state machines 310 included inthe HARQ controller 300. Such a control state needs to be held only whenACK/NAK Delay is 2 slots because the data channel turbo decoder 430 mustdecode new data every slot only when ACK/NAK Delay is 1 slot. However,when ACK/NAK Delay is 2 slots, the data channel turbo decoder 430 may bein the process of decoding data received at a previous slot. In thiscase, the HARQ controller 300 must wait until an operation of the datachannel turbo decoder 430 is completed. Furthermore, since only one datachannel turbo decoder 430 is used in embodiment of the presentinvention, this state is necessarily required when the ACK/NAK Delay is2 slots, in order to prevent data collision. That is, by employing thefourth state S4, it is possible to process a plurality of packet datachannels using one turbo decoder even when ACK/NAK Delay is 2 slots. TheHARQ controller 300 transitions to the fifth state S5, if the datachannel turbo decoder 430 becomes available while the HARQ controller300 is waiting in the fourth state S4.

[0113] In the fifth state S5, the HARQ controller 300 controls turbodecoding. The fifth state S5 becomes a ‘decoding state’. That is, in thefifth state S5, the HARQ controller 300 provides various informationnecessary for turbo decoding to the data channel turbo decoder 430. Theinformation necessary for turbo decoding can become a size of an encoderpacket (EP) and ACID. The HARQ controller 300 provides the aboveinformation to the data channel turbo decoder 430 and thereafter, waitsuntil a decoding operation is done. However, there is a case where turbodecoding is performed for an excessively long time, or turbo decodingmust be performed early by other information. In this case, the HARQcontroller 300 can compulsorily stop turbo decoding by outputting anintentional stop signal. The HARQ controller 300 transitions to thesixth state S6, when the turbo decoding is completed or intentionallyended.

[0114] In the sixth state S6, the HARQ controller 300 transmits aresponse signal (ACK/NAK) for a subpacket received over a reversechannel according to the decoding result of the data channel turbodecoder 430. That is, the sixth state S6 is a ‘response signal (ACK/NAK)transmission state’. Therefore, the HARQ controller 300 controls theresponse signal transmitter 440, and as a result of the decoding, ifthere is no error, the HARQ controller 300 transmits ACK over a reversechannel. In contrast, if an error has occurred, the HARQ controller 300transmits NAK over a reverse channel. Since the sixth state S6 is thelast state of the HARQ controller 300, the HARQ controller 300transitions to the first state S1 after transmitting the decodingresult, and waits again in the initial state to process the next state.When ACK/NAK Delay is 2 slots, the HARQ controller 300 includes two HARQstate machines 310. In this case, the two HARQ state machines 310 cansimultaneously perform the first state S1 or the sixth state S6.However, the other states S2, S3, S4 and S5 are never usedsimultaneously.

[0115] Next, an internal structure of the HARQ controller 300 will bedescribed below. FIG. 6 is a diagram illustrating the connection betweenan HARQ state machine and a state function section in an HARQ controlleraccording to an embodiment of the present invention. With reference toFIG. 6, a detailed description will be made of the connection between anHARQ state machine and a state function section according to anembodiment of the present invention.

[0116] In FIG. 6, a state function section 335 represents a statefunction section separated from the state function and data pathcontroller 330 of FIG. 5. The HARQ state machines 310 control statetransition of the first to sixth states S1 to S6 according to an HARQcontrol flow. That is, the HARQ state machines 310 output statetransition signals. The state function section 335 controls other blocks(local function blocks) 401, . . . , 403 to control operations performedin the respective states. The other blocks 401, . . . , 403 illustratedin FIG. 6 can include the processor 400 and the control channel decoder410 to the response signal transmitter 440 of FIG. 5, excluding the HARQcontroller 300, and can also include other blocks which are notillustrated in FIG. 5. That is, the state function section 335 receivesstate signals output from the HARQ state machines 310, and controloperations depending on the state signal.

[0117] The HARQ state machines 310 receive information on current statesand information on whether ACK/NAK Delay is 1 slot or 2 slots, and alsoreceives an operation-done signal Fi_DONE from the state functionsection 335. Since two HARQ state machines 310 are provided when ACK/NAKDelay is 2 slots, the operation-done signal is applied to the respectiveHARQ state machines 310. Upon receiving the operation-done signal, theHARQ state machines 310 output next state signals. At this point, sincetwo HARQ state machines 310 are provided when ACK/NAK Delay is 2 slots,the respective HARQ state machines 310 output corresponding stateinformation. In addition, the HARQ state machines 310 output a stateenable signal Si_EN to the state function section 335 so as to perform acontrol operation according to the state information and thecorresponding state.

[0118] That is, the HARQ state machines 310 are different in theirnumber and operation according to whether ACK/NAK Delay is 1 slot or 2slots. Herein, a detailed description of the embodiment of the presentinvention will be made with reference to when the number of the HARQstate machines 310 is 1 or 2.

[0119] When ACK/NAK Delay is 1 slot, one HARQ state machine 310 isprovided, so only one state enable signal is output to the statefunction section 335. Also, only one operation-done signal is providedfrom the state function section 335 to the HARQ state machine 310.However, when ACK/NAK Delay is 2 slots, two HARQ state machines 310 areprovided. In this case, HARQ state machines 310 are divided into a firstHARQ state machine (or odd HARQ state machine (OHSM)) and a second HARQstate machine (or even HARQ state machine (EHSM)). The first and secondHARQ state machines have the same structure, and compared with when oneHARQ state machine is provided, the fourth state S4 is further providedas illustrated in Table 1. That is, the first and second HARQ statemachines perform the same operation in which they generate the sameoutputs in response to the same inputs. However, this does not mean thatthe two HARQ state machines are identical in state progress. That is,OHSM and EHSM used are changed according to ACK/NAK Delay as illustratedin Table 2 below. TABLE 2 ACK_DELAY (slots) # of State Machine to use 11 (OHSM) 2 2 (OHSM, EHSM)

[0120] When this is implemented in a mobile station, in order to acceptboth ACK/NAK Delay=1 slot and ACK/NAK Delay=2 slots, 2 HARQ statemachines are provided, and for ACK/NAK Delay=1 slot, only one HARQ statemachine is enabled and the fourth state S4 is excluded preferably.

[0121] Now, state transition of the respective states will be describedwith reference to FIG. 7. FIG. 7 is a state transition diagram of anHARQ controller according to an embodiment of the present invention.

[0122] The first state S1 represents a state where the HARQ controller300 is waiting for decoding of a packet data control channel to becompleted after performing initialization on a register, as described inconjunction with Table 1. In FIG. 7, step 500 represents a state wherethe HARQ controller 300 is waiting while holding the first state S1. Ifa decoding-done signal of a packet data control channel is received fromthe state function section 335 while the waiting state is held,transition occurs to the second state S2 in step 502. When transition tothe second state S2 occurs, the HARQ state machine 310 calculates instep 506 such parameters as a modulation level necessary fordemodulation and a Walsh code, using the decoding result of the packetdata control channel in the first state S1. Furthermore, in the secondstate S2, the calculated parameters are error-checked. As a result ofthe error check, if a parameter error is detected, the HARQ statemachine 310 proceeds to step 504 where it notices occurrence of theparameter error, and then transitions back to the first state S1 (step500). In contrast, when no error has occurred in the calculatedparameters, the HARQ state machine 310 proceeds to step 508 where itdetects a correct parameter of a packet data channel, delivers thedetected parameter to the state function section 335, and thentransitions to the third state S3. As a result of the parametercalculation in step 506, if a received message is a Control HoldMode/Cell Switching (CHM/CS) related signaling message, the HARQ statemachine 310 transitions not to the third state S3 but to the sixth stateS6.

[0123] If transition to the third state S3 occurs, the HARQ statemachine 310 demodulates a packet data channel in step 512. Suchdemodulation is controlled by the state function section 335, and theHARQ state machine 310 waits for the demodulation to be done.Thereafter, if the demodulation is done, the HARQ state machine 310performs state transition according to ACK/NAK Delay=1 slot or 2 slots.If ACK/NAK Delay is 1 slot, the HARQ state machine 310 proceeds to step516 where it transitions to the fifth state S5. If ACK/NAK Delay is 2slots, the HARQ state machine 310 proceeds to step 514 where ittransitions to the fourth state S4. First, a description will be madewhen ACK/NAK Delay is 2 slots, i.e., where the HARQ state machine 310proceeds to step 514 and transitions to the fourth state S4.

[0124] When transition to the fourth state S4 takes place, the first orsecond HARQ state machine holds the waiting state since the data channelturbo decoder 430 is being used not by the HARQ state machine itself butby another HARQ state machine, When another HARQ state machine ends useof the data channel turbo decoder 430, the first or second HARQ statemachine transitions to the fifth state S5 in step 520.

[0125] If transition occurs from the third state S3 or the fourth stateS4 to the fifth state S5, the HARQ state machine 310 waits for turbodecoding to be completed in step 522. At this point, the turbo decodingis controlled by the state function section 335. If a turbodecoding-done signal is received from the state function section 335,the HARQ state machine 310 proceeds to step 524 where it transitions tothe sixth state S6. The sixth state S6 represents a step in whichACK/NAK is transmitted as described in conjunction with Table 1. Iftransition to the sixth state S6 takes place, the state function section335 controls the response signal transmitter 440 to transmit ACK or NAKover a reverse channel according to the turbo decoding result. Iftransmission of ACK or NAK is done, the state function section 335outputs an ACK/NAK transmission-done signal to the HARQ state machine310. As a result, the HARQ state machine 310 proceeds to step 528 whereit holds the first state S1.

[0126] Now, operation timing of the HARQ state machine 310 based onACK/NAK Delay will be described with reference to the accompanyingdrawings. FIG. 8 is an operational timing diagram of first or secondHARQ state machines for ACK/NAK Delay=1 slot, and FIG. 9 is anoperational timing diagram of first and second HARQ state machines forACK/NAK Delay=2 slots.

[0127] Referring to FIG. 8, a description will be made when ACK/NAKDelay is 1 slot. In FIG. 8, if a decoding operation of a k^(th) packetdata control channel (PDCCH) is completed, a decoding-done signal istransmitted to the first HARQ state machine OHSM. The first HARQ statemachine OHSM then controls state transition in response to a k^(th)signal. If a decoding-done signal of a (K+1)^(th) packet data controlchannel is received again at the next slot, the first HARQ state machineOHSM controls next state transition in response thereto. That is, whenACK/NAK Delay is 1 slot, the second HARQ state machine EHSM performs nooperation.

[0128] Referring to FIG. 9, a description will be made when ACK/NAKDelay is 2 slots. In FIG. 9, if a decoding operation of a k^(th) packetdata control channel (PDCCH) is completed, a decoding-done signal istransmitted to the first HARQ state machine OHSM. The first HARQ statemachine OHSM then controls transition of the first to sixth states S1 toS6 for a 2-slot period, i.e., for the K^(th) and (K+1)^(th) slots. Inaddition, an operation in each state is controlled by the state functionsection 335 according to a state transition signal from the first HARQstate machine OHSM. If a decoding operation of a (K+1)^(th) packet datacontrol channel (PDCCH) is completed, a decoding-done signal istransmitted to the second HARQ state machine EHSM. Therefore, the secondHARQ state machine EHSM controls transition of the first to sixth statesS1 to S6 for a 2-slot period, i.e., for the (K+1)^(th) and (K+2)^(th)slots. As illustrated in FIG. 9, if no packet data control channelsignal is received at the (K+2)^(th) slot, the first HARQ state machineOHSM holds an idling state. Thereafter, if a packet data control channelsignal is received at a (K+3)^(th) slot, the second HARQ state machineEHSM operates. In this order, the first HARQ state machine OHSM and thesecond HARQ state machine EHSM operate.

[0129] In order for the first HARQ state machine OHSM and the secondHARQ state machine EHSM to operate with a one-slot offset as illustratedin FIG. 9, a signal for controlling the operation is required. Such acontrol signal cannot be generated by the HARQ state machine 310 or thestate function section 335. Therefore, a separate device is required. Atthis point, necessary input signals include information on ACK/NAKDelay, a synchronization signal SYNC_125, and a system time clockSYS_TIME_125[0]. If it is determined from the input signals that ACK/NAKDelay is 2 slots, signals ODD_125 and EVEN_125 capable of selecting thefirst HARQ state machine OHSM or the second HARQ state machine EHSM insynchronism with the synchronization signal and the system time clockare generated.

[0130]FIG. 10 is an activation control timing diagram of first andsecond HARQ state machines for ACK/NAK Delay=1 slot according to theembodiment of the present invention, and FIG. 11 is an activationcontrol timing diagram of first and second HARQ state machines forACK/NAK Delay=2 slots according to the embodiment of the presentinvention. With reference to FIGS. 10 and 11, a detailed descriptionwill now be made of activation control timing of the first and secondHARQ state machines according to the embodiment of the presentinvention.

[0131] In FIGS. 10 and 11, output types are determined by a value ofACK/NAK Delay, a synchronization signal SYNC_125 indicating a slotboundary of a reception stage, and SYSM_TIME_125[0] which is a leastsignificant bit (LSB) of a system time indicating a 1.25 msec unit.First, a description of FIG. 10 will be made. As illustrated, whenACK_DELAY is 1 slot, a first state machine selection signal ODD_125applied to the first HARQ state machine OHSM and a second state machineselection signal EVEN_125 applied to the second HARQ state machine EHSMare output in a High state and a Low state, respectively. This is toenable only the first HARQ state machine OHSM to perform a statetransition operation, and prevent the second HARQ state machine EHSMfrom performing state transition. Therefore, the system timeSYS_TIME_125 alternately holds a Low state and a High state by the 1.25msec, and the synchronization signal SYNC_125 also instantaneously holdsa High state at a start point of a 1.25 msec slot.

[0132] Next, with reference to FIG. 11, a description will be made whenACK/NAK Delay is 2 slots. As illustrated in FIG. 11, the first statemachine selection signal ODD_125 applied to the first HARQ state machineOHSM alternates between a Low state and a High state by the 1.25 msec.Also, the second state machine selection signal EDD_125 applied to thesecond HARQ state machine EHSM alternates between a Low state and a Highstate by the 1.25 msec. In addition, the first state machine selectionsignal ODD_125 and the second state machine selection signal EVEN_125always output exclusive states. For example, when the first statemachine selection signal ODD_125 is in a High state, the second statemachine selection signal EVEN_125 is in a Low state, and when the firststate machine selection signal ODD_125 is in a Low state, the secondstate machine selection signal EVEN_125 is in a High state. The systemtime signal and the synchronization signal have the same waveforms asthe corresponding signals illustrated in FIG. 10.

[0133] In the mobile communication system, ACK/NAK Delay becomes anentire system delay time. Therefore, when ACK/NAK Delay is 1 slot,ACK_DELAY can be 0 in the mobile station, and when ACK/NAK Delay is 2slots, ACK_DELAY can be 1 in the mobile station. As a result, transitionto the next state can be illustrated as shown in Table 3 according tocurrent states of the HARQ state machine 310 and signal outputs from thestate function section 335. TABLE 3 Current INPUT NEXT State ACK_DELAYF1_DONE F2_DONE F3_DONE F4_DONE F5_DONE F6_DONE STATE S1 X 0 X X X X XS1 X 1 X X X X X S2 S2 X X 000 X X X X S2 X X 001 X X X X S2 X X 010 X XX X S2 X X 011 X X X X S2 X X 100 X X X X S3 X X 101 X X X X S1 X X 110X X X X S6 X X 111 X X X X S6 S3 0 X X 0 X X X S3 0 X X 1 X X X S5 1 X X0 X X X S3 1 X X 1 X X X S4 S4 0 X X X 0 X X NA 0 X X X 1 X X NA 1 X X X0 X X S4 1 X X X 1 X X S5 S5 X X X X X 0 X S5 X X X X X 1 X S6 S6 X X XX X X 0 S6 X X X X X X 1 S1

[0134] In Table 3, Fi (where i=1 to 6) refers to an output signal of thestate function section 335 in an i^(th) state. For example, F1_DONErefers to an operation-done signal output from the state functionsection 335 in the first state S1, and F2_DONE means an operation-donesignal output from the state function section 335 in the second stateS2. In addition, ACK_DELAY refers to a delay time in a mobile station,and a part represented by X refers to “don't care.”

[0135]FIG. 12 is a state transition timing diagram of a first HARQ statemachine for ACK/NAK Delay=1 slot according to an embodiment of thepresent invention. With reference to FIG. 12, a detailed descriptionwill now be made of a state transition operation of the first HARQ statemachine for ACK/NAK Delay=1 slot. In FIG. 12, a state is represented byOSi. That is, OS1 indicates the first state S1, and OS2 indicates thesecond state S2. In order to indicate a state in the first HARQ statemachine OHSM, the states are represented by OS1, OS2, . . . in thedrawing.

[0136] When the first state S1 is being held, the first HARQ statemachine OHSM receives a packet data control channel signal and decodesthe received packet data control channel signal. Therefore, the statefunction section 335 outputs an F1_DONE signal at a particular time t1.The first HARQ state machine OHSM then detects this at a time t2, andtransitions to the second state S2. If an F2_DONE signal is output fromthe state function section 335 while the second state S2 is being held,the first HARQ state machine OHSM holds the second state S2, returns tothe first state S1, or transitions to the third state S3 or the sixthstate S6. The 4 kinds of state transitions are performed based on thevalues output from the state function section 335, illustrated in Table3. FIG. 12 shows transition to the third state S3, the most generalstate transition, and this will be described below.

[0137] When state transition to the third state S3 occurs, the firstHARQ state machine OHSM disregards other signals, e.g., F1_DONE orF2_DONE, received from the state function section 335, if any, anddetermines whether an F3_DONE signal is output from the state functionsection 335. When the F3_DONE signal is output from the state functionsection 335 at a time t4, the first HARQ state machine OHSM transitionsto the fifth state S5 since ACK/NAK Delay is 1 slot. Thereafter, thefirst HARQ state machine OHSM waits for an F5_DONE signal to be receivedfrom the state function section 335. The state function section 335outputs F5_DONE when a control operation in the fifth state S5 is done.In FIG. 12, F5_DONE is output at a time t5. When the F5_DONE is output,the first HARQ state machine OHSM transitions to the sixth state S6.

[0138] The first HARQ state machine OHSM holds the sixth state S6, andwaits for an F6_DONE signal to be output from the state function section335. As illustrated in FIG. 12, the F6_DONE signal can be output when a1.25 msec period expires. Since the first HARQ state machine OHSM cantransition to the first state S1, its operation is not affected at thenext slot. That is, since the first HARQ state machine OHSM can receivethe F6_DONE signal at a time t6 and then immediately transition to thefirst state S1 at a time t7, data processing is not affected at the nextslot.

[0139] Next, operations in times t7 to t9 will be described. At a timet7, the first HARQ state machine OHSM holds the first state S1. If anF1_DONE signal is received from the state function section 335 at a timet8, the first HARQ state machine OHSM transitions to the second stateS2, and then waits for an F2_DONE signal to be output from the statefunction section 335. The state function section 335 performs a controloperation in the second state S2, and outputs an F2_DONE signal when thecontrol operation is completed. Here, if the F2_DONE signal is “101” asshown in Table 3, the first HARQ state machine OHSM transitions to thefirst state S1 because F2_DONE=101 is a signal requesting transitionback to the first state S1. If F2_DONE is “110” or “111” requestingtransition to the sixth state S6, the first HARQ state machine OHSMtransitions to the sixth state S6.

[0140]FIG. 13 is a state transition timing diagram of a first HARQ statemachine and a second HARQ state machine for ACK/NAK Delay=2 slotsaccording to an embodiment of the present invention. With reference toFIG. 13, a detailed description will now be made of a state transitionoperation of a first HARQ state machine OHSM and a second HARQ statemachine EHSM for ACK/NAK Delay=2 slots. In FIG. 13, a state of the firstHARQ state machine OHSM is represented by OSi. That is, OS1 indicatesthe first state S1 of the first HARQ state machine, and OS2 indicatesthe second state S2 of the first HARQ state machine. In order toindicate a state in the first HARQ state machine OHSM, the states arerepresented by OS1, OS2, . . . in the drawing. A state of the secondHARQ state machine is represented by ESi. That is, ES1 indicates thefirst state S1 of the second HARQ state machine, and ES2 indicates thesecond state S2 of the second HARQ state machine. In order to indicate astate in the second HARQ state machine EHSM, the states are representedby ES1, ES2, in the drawing. In addition, OFi_DONE and EFi_DONErepresent an output to the first HARQ state machine OHSM and an outputto the second HARQ state machine EHSM, respectively.

[0141] The first HARQ state machine OHSM, when it holds the first stateS1, receives a packet data control channel signal and decodes thereceived packet data control channel signal. Therefore, if the statefunction section 335 outputs an F1_DONE signal at a particular time t1,the first HARQ state machine OHSM detects this, and then transitions tothe second state S2. If an F2_DONE signal is output from the statefunction section 335 while the second state S2 is being held, the firstHARQ state machine OHSM holds the second state S2, returns to the firststate S1, or transitions to the third or sixth state S3 or S6 accordingto the type of output signal. The 4 kinds of state transitions areperformed based on the values output from the state function section335, illustrated in Table 3. FIG. 13 shows transition to the third stateS3, the most general state transition, and this will be described below.

[0142] When state transition to the third state S3 occurs, the firstHARQ state machine OHSM disregards other signals, e.g., F1_DONE orF2_DONE, received from the state function section 335, if any, anddetermines whether an F3_DONE signal is output from the state functionsection 335. When the F3_DONE signal is output from the state functionsection 335 at a time t4, the first HARQ state machine OHSM transitionsto the fourth state S4 since ACK/NAK Delay is 2 slots. Thereafter, thefirst HARQ state machine OHSM transitions to the fifth state S5, when anF4_DONE signal is received from the state function section 335. Thefifth state S5 continues over a boundary of a 1.25 msec slot. That is,the first HARQ state machine OHSM continues the fifth state S5 over the1.25 msec slot's boundary which is a time t6. While holding the fifthstate S5 in this way, the first HARQ state machine OHSM waits for anF5_DONE signal to be received.

[0143] In the case where the next packet data is received after the timet6, if a first state-done signal F1_DONE is output from the statefunction section 335 at a time t7, the second HARQ state machine EHSMtransitions to the second state S2. If the second state S2 is completed,i.e., if an F2_DONE signal is output from the state function section 335at a time t8, the second HARQ state machine EHSM transitions to thethird state S3. There are 4 possible transitions from the second stateS2. FIG. 13 shows transition to the third state S3.

[0144] The state function section 335 performs a control operation forthe third state S3, and the second HARQ state machine EHSM holds thethird state S3. If the control operation for the third state S3 iscompleted, the state function section 335 outputs an F3_DONE signal at atime t9. The second HARQ state machine EHSM then transitions to thefourth state S4. The second HARQ state machine EHSM holds the fourthstate S4 until the first HARQ state machine OHSM ends the fifth stateS5. That is, the state function section 335 outputs an F4_DONE signal tothe second HARQ state machine EHSM at the next clock of a time t10 atwhich the fifth state S5 of the first HARQ state machine OHSM iscompleted. Accordingly, the second HARQ state machine EHSM cantransition to the fifth state S5 at a time t11.

[0145] In FIG. 13, since ACK/NAK Delay is 2 slots, a sixth state-donesignal F6_DONE is output at a time t13 which is the last time of thesecond 1.25 msec slot. Accordingly, the first HARQ state machine OHSMcan transition to the first state S1.

[0146] According to the timing diagram of FIG. 13, the state functionsection 335 must be formed as follows.

[0147] First, two first state processors that control the first state S1must be provided for the first HARQ state machine OHSM and the secondHARQ state machine EHSM because the first HARQ state machine OHSM andthe second HARQ state machine EHSM can simultaneously hold the firststate S1.

[0148] Second, since second to fifth state processors controlling thesecond to fifth states S2 to S5 are not simultaneously held in any case,they are separately formed, and they can be designed so that the outputsignals are processed in the first HARQ state machine OHSM and thesecond HARQ state machine EHSM.

[0149] Third, the sixth state S6, as mentioned above, is a state thatcan be simultaneously performed by the first HARQ state machine OHSM andthe second HARQ state machine EHSM. Therefore, two sixth stateprocessors that process the sixth state S6 must be provided so as tooperate in association with the first HARQ state machine OHSM and thesecond HARQ state machine EHSM.

[0150] That is, the state function section 335 has state processors forcorresponding states in order to process internal functions, and thestate processors perform operations that must be performed in therespective states. As to the number of the state processors, two stateprocessors are provided for each of the first and sixth processorsprocessing the first and sixth states, and a single state processor isprovided for each of the second to fifth state processors. Therefore,the state function section 335 can be comprised of a total of 8 internalblocks.

[0151] It can be understood from FIGS. 12 and 13 that the fifth state S5cannot be simultaneously held. Therefore, ACK/NAK Delay=1 slot andACK/NAK Delay=2 slots are both satisfied with only one the data channelturbo decoder 430.

[0152] Referring to FIG. 5, the output buffer controller 340 will bedescribed. Generally, in a high-speed data modem, e.g., an EV-DV modem,timing and a hardware structure for data exchange with an output bufferof a turbo decoder, an HARQ controller and a processor (CPU or host)must have several characteristics listed below for efficient datatransmission. That is, unlike a structure of a signal output buffer usedin the existing CDMA2000 1× forward supplemental channel (F-SCH), astructure of an output buffer of a turbo decoder has the followingstructural characteristics in order to increase a turbo decoding timeand a data rate.

[0153] (1) Fundamentally, a double output buffer structure is used.

[0154] (2) In order to reduce an interrupt handling load of theprocessor (CPU or host), a maximum of 4 output frames (decodedinformation blocks or encoder packets) are sequentially stored in theoutput buffer. Thereafter, all data in the output buffer is transmittedto the processor at the same time after a lapse of a particular time (5msec at the least).

[0155] (3) A variable control method is provided in which a systemselects one of two output buffer operating methods according to a changein ACK_DELAY (1 slot or 2 slots) of a particular reverse channel duringcell setup.

[0156] (4) Since a forward packet data channel (F-PDCH) is packet data,it can transmit data on a non-real-time basis, unlike the existingforward supplemental channel (F-SCH). However, since a near-real-timeservice must be supported, F-PDCH should be able to support fast datatransmission, if possible.

[0157] To this end, unlike the existing F-SCH output buffer, a variableoutput buffer read/write controller is required. A controller performingsuch a control operation is an output buffer controller (OBUFC). In thepresent invention, the output buffer controller 340 satisfying suchconditions is included in the HARQ controller 300. That is, in theembodiment of the present invention, as mentioned above, the outputbuffer controller 340 having a different transmission scheme accordingto ACK_DELAY is provided and operated in association with the HARQ statemachine 310 of the HARQ controller 300.

[0158]FIG. 14 is a diagram illustrating a control flow between an HARQcontroller and its peripheral devices according to an embodiment of thepresent invention. With reference to FIGS. 5 and 14, a detaileddescription will now be made of a control flow between an HARQcontroller and its peripheral devices according to embodiment of thepresent invention. A description of FIG. 14 will be made in order ofreference numerals 1, 2, . . . , 14, which represent steps.

[0159] Step 1: If a mobile station is set to an EV-DV physical channelsetup mode of Radio Configuration 10 (RC-10) which is one of severalCDMA2000 1× physical channel setup modes by upper layer signaling, anupper layer transmits an HARQ activation signal HARQ_ACTIVE indicatinginitiation of an operation of the HARQ controller 300.

[0160] Step 2: The HARQ controller 300 enables the control channeldecoder 410 by outputting a control channel decoder enable signalPDCCH_DEC_EN to the control channel decoder 410.

[0161] Step 3: The control channel decoder 410, if enabled, receives adecoding signal for a forward packet data control channel (F-PDCCH) andperforms a decoding operation according to the decoding signal. Ifdecoding is completed, the control channel decoder 410 transmits acontrol channel decoding-done signal PDCCH_DEC_DONE and decoding-relatedinformation to the HARQ controller 300.

[0162] Step 4: The HARQ controller 300 determines its next operationusing information received in Step 3 from the control channel decoder410. If a MAC ID in a signal received from the control channel decoder410 indicates the HARQ controller 300 itself, i.e., if a MAC_ID_OKsignal is received, related information for performing a receptionoperation of forward packet data received over a forward packet datachannel (F-PDCH) is generated. However, when the MAC ID does notindicate the HARQ controller 300, the HARQ controller 300 repeatedlyperforms Step 3 and waits until a MAC ID indicating the HARQ controller300 is received.

[0163] Step 5: If there is a forward packet data channel (F-PDCH)assigned to the mobile station, the HARQ controller 300 outputs a datachannel demodulation enable signal PDCH_DEMOD_EN to the data channeldemodulator 420 to enable the data channel demodulator 420.

[0164] Step 6: Upon receiving the data channel demodulation enablesignal, the data channel demodulator 420 performs a demodulationoperation, a demapping operation, and a QCTC clearing/combiningoperation.

[0165] Step 7: If an operation of Step 6 is completed, the data channeldemodulator 420 delivers a data channel demodulation-done signal to theHARQ controller 300.

[0166] Step 8: If a data channel demodulation operation is completed,the HARQ controller 300 outputs a data channel turbo decoder enablesignal PDCH_TURBO_EN to the data channel turbo decoder 430 to read codesymbols stored in a QCTC buffer. Thereafter, the data channel turbodecoder 430 performs turbo decoding on the read code symbols.

[0167] Step 9: If the decoding operation is completed, the data channelturbo decoder 430 outputs a turbo decoding-done signal PDCH_TURBO_DONEto the HARQ controller 300.

[0168] Step 10: The HARQ controller 300 performs CRC check using thedata decoded by the data channel turbo decoder 430. If a CRC result ofthe decoded data is “BAD,” the HARQ controller 300 directs an operationfor improving decoding performance of the data channel turbo decoder430, and controls an external buffer.

[0169] Step 11: The HARQ controller 300 controls the response signaltransmitter 440 according to the decoding result or its own decision totransmit ACK or NAK over a reverse response channel (R-ACKCH).

[0170] Step 12: The HARQ controller 300 generates an interrupt fortransmitting, to the upper layer, data stored in an output buffer afterbeing received over a forward packet data channel and finally decoded bythe data channel turbo decoder 430.

[0171] Step 13: The upper layer transfers, to its upper layer, forwardpacket data stored in an output buffer of the data channel turbo decoder430 in response to the interrupt signal received from the HARQcontroller 300.

[0172] Step 14: If transfer of received data on a forward packet datachannel stored in the output buffer of the data channel turbo decoder430 is completed, the upper layer informs the HARQ controller 300 thatreception of the forward packet data channel is completed.

[0173] Now, operations of Step 1 to Step 14 will be described separatelyfor ACK/NAK Delay=1 slot and ACK/NAK Delay=2 slots. First, operations ofStep 1 to Step 14 will be described for ACK/NAK Delay=1 slot.

[0174] For ACK/NAK Delay=1 slot, an operation of the data channel turbodecoder 430 is completed before each slot. Therefore, the data channelturbo decoder 430 generates an enable signal PDCH_TURBO_EN of the datachannel turbo decoder 430 immediately after a demodulation-done signalPDCH_DEMOD_DONE of the data channel demodulator 420. A decodingoperation of the data channel turbo decoder 430 is completed within oneslot. That is, a range of the maximum time is limited within 1 slot, ifa CRC check result for the decoded data from the data channel turbodecoder 430 is “BAD” or “GOOD,” or if early stop is performed before amaximum decoding repetition number. Therefore, if it is determined thata decoding operation of the data channel turbo decoder 430 continues for1 slot or more, the HARQ controller 300 stops the decoding operation bycompulsion before a 1-slot boundary. In this manner, the turbo operationis completed within one slot. Since the entire HARQ operation isperformed within 1 slot in this way, HARQ operations in which an ARQchannel is received at consecutive slots are performed independent ofeach other,

[0175] Next, operations of Step 1 to Step 14 will be described forACK/NAK Delay=2 slots.

[0176] For ACK/NAK Delay=2 slots, the data channel turbo decoder 430 canperform a decoding operation over a first slot boundary up to a secondslot boundary after receiving a subpacket. Here, an ARQ channel may bereceived over consecutive slots. In this case, there is a time periodfor which HARQ operations are overlapped. Such an overlapping timeperiod is related only to an operation of the data channel turbo decoder430, and is not related to an operation of the data channel demodulator420 because the data channel demodulator 420 does not operate over thenext slot since a demodulation operation is performed within a 1.25 msecslot where packet data is received. However, the data channel turbodecoder 430 starts its decoding operation at a slot where packet data isreceived, and ends the decoding operation within the next 1.25 msecslot. Therefore, when data received at a first slot is continuouslyturbo decoded at a second slot, data received at the second slot iswaited until decoding of the data received at the first slot is done. Ifturbo decoding of the data received at the first slot is completed,turbo decoding is performed on the data received at the second slot. Thepacket data received at the second slot can also be continuously turbodecoded up to the third slot, like the packet data received at the firstslot.

[0177]FIG. 15 is a flowchart illustrating a procedure for controllingrespective states by an HARQ controller during data reception accordingto an embodiment of the present invention. With reference to FIG. 15, adetailed description will now be made of a procedure for controllingrespective states by an HARQ controller during data reception accordingto the present invention.

[0178] In step 600, the HARQ controller 300 holds an initial state whichis the first state S1. In the initial state of the first state S1, theHARQ controller 300 performs parameter initialization, and waits for adecoding result of a packet data control channel (PDCCH) by controllingthe control channel decoder 410. While waiting for a decoding result ofthe packet data control channel, the HARQ controller 300 determines instep 602 whether a decoding-done signal of the packet data controlchannel is received from the control channel decoder 410. If it isdetermined in step 602 that a decoding-done signal of the packet datacontrol channel is received, the HARQ controller 300 proceeds to step604, and if decoding of the packet data control channel is notcompleted, the HARQ controller 300 continuously performs the step 600.In step 604, the HARQ controller 300 holds a control state of the secondstate S2. In the second state S2, the HARQ controller 300 calculates aparameter for demodulation of the forward packet data channel andperforms a fast HARQ protocol.

[0179] Thereafter, the HARQ controller 300 determines in step 606whether a control message received over the packet data control channel(PDCCH) is a control message for a packet data channel (PDCH). If it isdetermine in step 606 that a control message for a packet data channelis received, the HARQ controller 300 proceeds to step 612. Otherwise,the HARQ controller 300 proceeds to step 608 where it determines whethera received message is a message for control hold mode/cell switching.The HARQ controller 300 performs such an operation for the followingreasons. Generally, in an upper layer, a command for an operation of acontrol hold mode (CHM) or cell switching (CS) controlled by messageexchange between a base station and a mobile station is delivered over aseparate control channel. However, when an operation should be rapidlydirected, such a command can be delivered from the base station to themobile station over PDCCH rather than the existing control channel.Therefore, not knowing when the base station will send such a message tothe mobile station, the mobile station determines whether such an upperlayer control message is received, at each PDCCH decoding, and if such amessage is detected, it must be rapidly delivered to the upper layer. Ifit is determined in step 608 that a message for control hold mode/cellswitching is received, the HARQ controller 300 proceeds to step 610where it delivers the received message to a MAC layer which is its upperlayer.

[0180] In step 612, the HARQ controller 300 determines whether theparameter calculated in step 604 is a non-creatable parameter. If anon-creatable parameter is detected, the HARQ controller 300 returns tostep 600 where it transitions to the first state S1. Otherwise, the HARQcontroller 300 proceeds to step 614 where it transitions to the thirdstate S3. In step 614, the HARQ controller 300 performs demodulation bycontrolling the data channel demodulator 420. Thereafter, if thedemodulation is done, the HARQ controller 300 determines in step 616whether the data channel turbo decoder 430 is in use. If it isdetermined in step 616 that the data channel turbo decoder 430 is inuse, the HARQ controller 300 proceeds to step 618 where it holds awaiting state of the fourth state S4. However, if it is determined instep 616 that the data channel turbo decoder 430 is not in use, the HARQcontroller 300 proceeds to step 620 where it holds a decoding state ofthe fifth state S5. The HARQ controller 300 proceeds from step 616 tostep 618 when ACK/NAK Delay is 2 slots and turbo decoding of packet datareceived at a previous slot is not done.

[0181] In step 620, the data channel turbo decoder 430 performs turbodecoding by controlling the data channel turbo decoder 430. If thedecoding operation of the data channel turbo decoder 430 is completed,the HARQ controller 300 proceeds to step 622 where it performs the sixthstate S6. The sixth state S6 represents an ACK/NAK transmission step,and in the sixth state S6, the HARQ controller 300 controls transmissionof ACK/NAK over a reverse channel according to a turbo decoding resultoutput from the data channel turbo decoder 430. Thereafter, the HARQcontroller 300 transitions to the first state S1.

[0182] As described above, a mobile communication system can reduce aload of an upper layer by disposing a physically structured HARQcontroller between a MAC layer and a physical layer, reduce a load of aCPU due to maximum driving clock, and reduce a data processing time. Inaddition, when N-channel HARQ is supported, the mobile communicationsystem can support both ACK/NAK Delay=1 slot and ACK/NAK Delay=2 slotsregardless of the number of channels, preventing an increase incomplexity of a mobile station. Moreover, in this manner, it is possibleto rapidly deliver control information on a traffic control channel tothe upper layer.

[0183] While the invention has been shown and described with referenceto a certain embodiment thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims.

What is claimed is:
 1. An apparatus for controlling the operation of thedata channel in a mobile communication system that simultaneously acontrol message over the data control channel and the data over the datachannel and supports hybrid automatic repeat request (HARQ), theapparatus: a physical layer for receiving the traffic data and thecontrol message from the data control channel and the date channelseparately and decoding the received traffic data and control data; aphysical layer's HARQ controller for calculating the decoded resultsreceived from the physical layer and controlling the physical layeraccording to the calculating result.
 2. The apparatus of claim 1,wherein the physical layer's HARQ controller comprises: an HARQ statemachine for controlling state transition of an initial state forinitializing parameters while waiting for a control message to bereceived over the packet data control channel received from the physicallayer, a decoding state for decoding the control message, a controlstate for calculating the decoding result, a demodulation state fordemodulating packet data on the packet data channel, a decoding statefor turbo decoding the demodulated packet data, and a response state fortransmitting the turbo-decoding result; and a state function section forcontrolling state transition of the HARQ state machine depending on aprocessing result of the physical layer.
 3. The apparatus of claim 1,further comprising a data path processor for controlling a processingpath of data received over the packet data channel.
 4. The apparatus ofclaim 1, further comprising an output buffer controller for storing dataobtained by demodulating and decoding data received over the packet datachannel and outputting the stored data to the HARQ controller.
 5. Theapparatus of claim 2, wherein the HARQ state machine is dualized.
 6. Theapparatus of claim 5, wherein if a response delay time comprises 2slots, each of the dualized HARQ state machines alternately controls thestate transition for 2 slots for the data received over the packet datachannel.
 7. The apparatus of claim 6, wherein when transmitting a signalfor decoding of the packet data to the physical layer, the HARQ statemachine controls transition to a waiting state until an operation of thedecoder is ended.
 8. The apparatus of claim 7, wherein the statefunction section comprises: first state processors for performingcontrol operations of the associated dualized HARQ state machines in theinitial state; a second state processor for performing controloperations of the HARQ state machines in the control state; a thirdstate processor for performing control operations of the HARQ statemachines in the demodulation state; a fourth state processor forperforming control operations of the HARQ state machines in the waitingstate; a fifth state processor for performing control operations of theHARQ state machines in the decoding state; and sixths state processorsfor performing control operations of the associated HARQ state machinesin the response state.
 9. The apparatus of claim 1, wherein the physicallayer comprises one data channel turbo decoder.
 10. The apparatus ofclaim 1, wherein the decoder is a turbo decoder.
 11. An Apparatus ofclaim 1, wherein the physical layer's HARQ controller requests aretransmission of the traffic data to the physical layer of the mobilecommunication system when the result of the decoded data is bad.
 12. Anapparatus of claim 1, wherein the physical layer's HARQ controllertransmits the decoded data to an upper layer when the result of thedecoded data is good.
 13. An apparatus of claim 1, wherein the physicallayer comprises a decoder for decoding received control data, ademodulator for demodulating the data, and a decoder for decoding thedemodulated data.
 14. An apparatus of claim 13, wherein the physicallayer's HARQ controller determines whether to demodulate the datadepending on the decoded control data and outputs the decoded controldata to the demodulator and the decoder when the HARQ controllerdetermines to demodulate the data.
 15. An apparatus of claim 1, whereinthe physical layer's HARQ controller determines whether to demodulatethe data depending on the calculated result and outputs the result ofthe decoded control data to the physical layer when the HARQ controllerdetermines to demodulate the data.
 16. An apparatus of claim 1, whereinthe physical layer's HARQ controller determine whether to demodulate anddecode the received data depending on a decoding result of the controlmessage, outputs the decoded control message to the demodulator and thedecoder during demodulation and decoding of the received data, controlsoutput of a response signal according to a decoding result of the data.17. An apparatus of claim 1, wherein the physical layer's HARQcontroller delivers the decoded data to the upper layer.
 18. Anapparatus of HARQ (Hybrid Automatic Repeat Request) controller forretransmitting data in a mobile station of a mobile communicationsystem, the HARQ controller comprising: an HARQ state machine forreceiving state information from a physical layer and determining atransition result of a next state to a state function section; and astate function section for indicating an operation of the physical layeraccording to the determined result from the HARQ state machine.
 19. Theapparatus of claim 18, wherein the mobile station receives a datachannel and a control channel for transmitting control information fordecoding the data channel.
 20. The apparatus of claim 19, wherein themobile station includes a control channel decoder for decoding the datachannel, a data channel demodulator for demodulation the data, and adata channel decoder for decoding the demodulated data.
 21. Theapparatus of claim 19, wherein the state function section commands anoperation of any one of the control channel decoder, the data channeldemodulator and the data channel decoder, all of which are related totransition decision.